Create and import a custom python package - import doesn't work in the root

Question

I'm totally new to Python, and I want to create my first Python library for peronal uses.

I'm using Python 2.7.5, and running the IDLE interface.

So far, what I understood from the documentation and related questions is that:

• Python goes through a list of directories listed in sys.path to find scripts and libraries
• The package directory must contain a __init__.py file, which can be empty
• The module I want to create should be a modulename.py file with the code inside the package directory

(Sources: http://www.johnny-lin.com/cdat_tips/tips_pylang/path.html --- https://docs.python.org/2/tutorial/modules.html)

And here is what I tried that fails:

• Created a personal package directory C:\....\pythonlibs
• Created a subpackage dir C:\....\pythonlibs\package
• Created the __init__.py file inside both folders
• Created the mymodule.py file in the packacge dir

And then in the IDLE used this code:

import sys     
sys.path.append(r'C:\....\pythonlibs')

First issue:

Currently I have to do this append every time I enter the IDLE. How can I keep the directory in sys.path permanently just as there are a lot of other directories there?

Then I tried importing my package:

import pythonlibs #fails!! why?      
import pythonlibs.package #fails!! why?       
import package #works     

The error is: ImportError: No module named pythonlibs

Second issue?

This seems to be against the documentation, why can't I import from the root pythonlibs folder?

Answer 1

With line

sys.path.append(r'C:\....\pythonlibs')

you are instructing interpreter to start looking for modules (libraries) in this directory. Since this directory does not contain pythonlibs folder (the parent does), it can't import it.

Similarly - because it contains the module package, it can import it.